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  • How to enable the 2 concurrent (+1 console) sessions on Windows Server 2012

    - by Dai
    I have a Windows Server 2012 VM running on Windows Azure. I want to enable the ability for 2 simultaneous administrative sessions over Remote Desktop. This is permitted under the EULA for Windows Server 2012. This is NOT the same thing as the fully-blown Terminal Services / RDS feature. In Windows Server 2000 and 2003, multiple concurrent sessions (up to a limit of 2, plus the root /console session) were enabled by default (such that logging-in via RDP without logging-out first would create a new session rather than reconnecting to the old session). In Server 2008 and later it uses single-sessions by default, as this simplifies administration (as most people want to connect to old sessions). In Windows Server 2008 R2, you can add the MMC snap-ins for Remote Desktop Host Configuration which allows you to re-enable concurrent sessions. However, in Server 2012, after adding the Remote Administration snap-ins from Server Manager it seems the Remote Desktop Host Configuration snap-in has been removed. How can I re-enable the multiple concurrent sessions for Remote Desktop for Administration in Windows Server 2012?

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  • Can't get simple Apache VHost up and running

    - by TK Kocheran
    Unfortunately, I can't seem to get a simple Apache VHost online. I used to simply have one VHost which bound to all: <VirtualHost *:80>, but this isn't appropriate for security anymore. I need to have one VHost for localhost requests (ie my dev server) and one for incoming requests via my domain name. Here's my new VHost: NameVirtualHost domain1.com <VirtualHost domain1.com:80> DocumentRoot /var/www ServerName domain1.com </VirtualHost> <VirtualHost domain2.com:80> DocumentRoot /var/www ServerName domain2.com </VirtualHost> After I restart my server, I see the following errors in my log: [Wed Feb 16 11:26:36 2011] [error] [client ####.###.###.###] File does not exist: /htdocs [Wed Feb 16 11:26:36 2011] [error] [client ####.###.###.###] File does not exist: /htdocs What am I doing wrong? EDIT As per the answer give below, I have modified my configuration. Here are my configuration files: /etc/apache2/ports.conf: Listen 80 <IfModule mod_ssl.c> # If you add NameVirtualHost *:443 here, you will also have to change # the VirtualHost statement in /etc/apache2/sites-available/default-ssl # to <VirtualHost *:443> # Server Name Indication for SSL named virtual hosts is currently not # supported by MSIE on Windows XP. Listen 443 </IfModule> <IfModule mod_gnutls.c> Listen 443 </IfModule> Here are my actual defined sites: /etc/apache2/sites-enabled/000-localhost: NameVirtualHost 127.0.0.1:80 <VirtualHost 127.0.0.1:80> ServerAdmin ######### DocumentRoot /var/www <Directory /> Options FollowSymLinks AllowOverride None </Directory> <Directory /var/www/> Options Indexes FollowSymLinks MultiViews AllowOverride None Order allow,deny allow from all </Directory> ScriptAlias /cgi-bin/ /usr/lib/cgi-bin/ <Directory "/usr/lib/cgi-bin"> AllowOverride None Options +ExecCGI -MultiViews +SymLinksIfOwnerMatch Order allow,deny Allow from all </Directory> ErrorLog /var/log/apache2/error.log # Possible values include: debug, info, notice, warn, error, crit, # alert, emerg. LogLevel warn CustomLog /var/log/apache2/access.log combined Alias /doc/ "/usr/share/doc/" <Directory "/usr/share/doc/"> Options Indexes MultiViews FollowSymLinks AllowOverride None Order deny,allow Deny from all Allow from 127.0.0.0/255.0.0.0 ::1/128 </Directory> RewriteEngine On RewriteLog "/var/log/apache2/mod_rewrite.log" RewriteLogLevel 9 <Location /> <Limit GET POST PUT> order allow,deny allow from all deny from 65.34.248.110 deny from 69.122.239.3 deny from 58.218.199.147 deny from 65.34.248.110 </Limit> </Location> </VirtualHost> /etc/apache2/sites-enabled/001-rfkrocktk.dyndns.org: NameVirtualHost rfkrocktk.dyndns.org:80 <VirtualHost rfkrocktk.dyndns.org:80> DocumentRoot /var/www ServerName rfkrocktk.dyndns.org </VirtualHost> And, just for kicks, my main file: /etc/apache2/apache2.conf: # # Based upon the NCSA server configuration files originally by Rob McCool. # # This is the main Apache server configuration file. It contains the # configuration directives that give the server its instructions. # See http://httpd.apache.org/docs/2.2/ for detailed information about # the directives. # # Do NOT simply read the instructions in here without understanding # what they do. They're here only as hints or reminders. If you are unsure # consult the online docs. You have been warned. # # The configuration directives are grouped into three basic sections: # 1. Directives that control the operation of the Apache server process as a # whole (the 'global environment'). # 2. Directives that define the parameters of the 'main' or 'default' server, # which responds to requests that aren't handled by a virtual host. # These directives also provide default values for the settings # of all virtual hosts. # 3. Settings for virtual hosts, which allow Web requests to be sent to # different IP addresses or hostnames and have them handled by the # same Apache server process. # # Configuration and logfile names: If the filenames you specify for many # of the server's control files begin with "/" (or "drive:/" for Win32), the # server will use that explicit path. If the filenames do *not* begin # with "/", the value of ServerRoot is prepended -- so "/var/log/apache2/foo.log" # with ServerRoot set to "" will be interpreted by the # server as "//var/log/apache2/foo.log". # ### Section 1: Global Environment # # The directives in this section affect the overall operation of Apache, # such as the number of concurrent requests it can handle or where it # can find its configuration files. # # # ServerRoot: The top of the directory tree under which the server's # configuration, error, and log files are kept. # # NOTE! If you intend to place this on an NFS (or otherwise network) # mounted filesystem then please read the LockFile documentation (available # at <URL:http://httpd.apache.org/docs-2.1/mod/mpm_common.html#lockfile>); # you will save yourself a lot of trouble. # # Do NOT add a slash at the end of the directory path. # ServerRoot "/etc/apache2" # # The accept serialization lock file MUST BE STORED ON A LOCAL DISK. # #<IfModule !mpm_winnt.c> #<IfModule !mpm_netware.c> LockFile /var/lock/apache2/accept.lock #</IfModule> #</IfModule> # # PidFile: The file in which the server should record its process # identification number when it starts. # This needs to be set in /etc/apache2/envvars # PidFile ${APACHE_PID_FILE} # # Timeout: The number of seconds before receives and sends time out. # Timeout 300 # # KeepAlive: Whether or not to allow persistent connections (more than # one request per connection). Set to "Off" to deactivate. # KeepAlive On # # MaxKeepAliveRequests: The maximum number of requests to allow # during a persistent connection. Set to 0 to allow an unlimited amount. # We recommend you leave this number high, for maximum performance. # MaxKeepAliveRequests 100 # # KeepAliveTimeout: Number of seconds to wait for the next request from the # same client on the same connection. # KeepAliveTimeout 15 ## ## Server-Pool Size Regulation (MPM specific) ## # prefork MPM # StartServers: number of server processes to start # MinSpareServers: minimum number of server processes which are kept spare # MaxSpareServers: maximum number of server processes which are kept spare # MaxClients: maximum number of server processes allowed to start # MaxRequestsPerChild: maximum number of requests a server process serves <IfModule mpm_prefork_module> StartServers 5 MinSpareServers 5 MaxSpareServers 10 MaxClients 150 MaxRequestsPerChild 0 </IfModule> # worker MPM # StartServers: initial number of server processes to start # MaxClients: maximum number of simultaneous client connections # MinSpareThreads: minimum number of worker threads which are kept spare # MaxSpareThreads: maximum number of worker threads which are kept spare # ThreadsPerChild: constant number of worker threads in each server process # MaxRequestsPerChild: maximum number of requests a server process serves <IfModule mpm_worker_module> StartServers 2 MinSpareThreads 25 MaxSpareThreads 75 ThreadLimit 64 ThreadsPerChild 25 MaxClients 150 MaxRequestsPerChild 0 </IfModule> # event MPM # StartServers: initial number of server processes to start # MaxClients: maximum number of simultaneous client connections # MinSpareThreads: minimum number of worker threads which are kept spare # MaxSpareThreads: maximum number of worker threads which are kept spare # ThreadsPerChild: constant number of worker threads in each server process # MaxRequestsPerChild: maximum number of requests a server process serves <IfModule mpm_event_module> StartServers 2 MaxClients 150 MinSpareThreads 25 MaxSpareThreads 75 ThreadLimit 64 ThreadsPerChild 25 MaxRequestsPerChild 0 </IfModule> # These need to be set in /etc/apache2/envvars User ${APACHE_RUN_USER} Group ${APACHE_RUN_GROUP} # # AccessFileName: The name of the file to look for in each directory # for additional configuration directives. See also the AllowOverride # directive. # AccessFileName .htaccess # # The following lines prevent .htaccess and .htpasswd files from being # viewed by Web clients. # <Files ~ "^\.ht"> Order allow,deny Deny from all Satisfy all </Files> # # DefaultType is the default MIME type the server will use for a document # if it cannot otherwise determine one, such as from filename extensions. # If your server contains mostly text or HTML documents, "text/plain" is # a good value. If most of your content is binary, such as applications # or images, you may want to use "application/octet-stream" instead to # keep browsers from trying to display binary files as though they are # text. # DefaultType text/plain # # HostnameLookups: Log the names of clients or just their IP addresses # e.g., www.apache.org (on) or 204.62.129.132 (off). # The default is off because it'd be overall better for the net if people # had to knowingly turn this feature on, since enabling it means that # each client request will result in AT LEAST one lookup request to the # nameserver. # HostnameLookups Off # ErrorLog: The location of the error log file. # If you do not specify an ErrorLog directive within a <VirtualHost> # container, error messages relating to that virtual host will be # logged here. If you *do* define an error logfile for a <VirtualHost> # container, that host's errors will be logged there and not here. # ErrorLog /var/log/apache2/error.log # # LogLevel: Control the number of messages logged to the error_log. # Possible values include: debug, info, notice, warn, error, crit, # alert, emerg. # LogLevel warn # Include module configuration: Include /etc/apache2/mods-enabled/*.load Include /etc/apache2/mods-enabled/*.conf # Include all the user configurations: Include /etc/apache2/httpd.conf # Include ports listing Include /etc/apache2/ports.conf # # The following directives define some format nicknames for use with # a CustomLog directive (see below). # If you are behind a reverse proxy, you might want to change %h into %{X-Forwarded-For}i # LogFormat "%v:%p %h %l %u %t \"%r\" %>s %O \"%{Referer}i\" \"%{User-Agent}i\"" vhost_combined LogFormat "%h %l %u %t \"%r\" %>s %O \"%{Referer}i\" \"%{User-Agent}i\"" combined LogFormat "%h %l %u %t \"%r\" %>s %O" common LogFormat "%{Referer}i -> %U" referer LogFormat "%{User-agent}i" agent # # Define an access log for VirtualHosts that don't define their own logfile CustomLog /var/log/apache2/other_vhosts_access.log vhost_combined # Include of directories ignores editors' and dpkg's backup files, # see README.Debian for details. # Include generic snippets of statements Include /etc/apache2/conf.d/ # Include the virtual host configurations: Include /etc/apache2/sites-enabled/ what else do I need to do to fix it? Should I be telling apache to listen on 127.0.0.1:80, or isn't it already listening there?

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  • ADSL to T1, Is it worth it for us?

    - by Jack Hickerson
    The company I work for has roughly 45-55 simultaneous users (local and remote/VPN) logged in at a given time. We currently subscribe to an ADSL connection but we have been experiencing slower upload/download speeds as our number of users increase. So, I have a few questions with regards to upgrading our connection to a t1 line. I am aware that the number of channels on a t1 line are much greater then that of our current ADSL connection, but I have heard that the number of active users on a t1 line should be no greater than ~30 for optimal performance. I would think this statement is dependent on what each user was using the connection for and could change depending on this variable. That being said, I have tried to break down how the line would be used in our organization based on our major departments: Sales (~60% of total users) - Everyday surfing, email, research, occasional streaming media Marketing (~15% of total users) - Heavy reliance on uploading/downloading, streaming media, file sharing Other (~25% of total users) - email, rare use of any connection intensive activities. I have considered keeping the ADSL for our local users and dedicating the t1 to our remote users (or vice versa) but the cost is significantly higher then what we had hoped for. All factors being equal (# of users, frequency of downloads/uploads from our current activities) Would you suspect a significant performance increase in making the transition to a t1 line from our current ADSL line? What are your thoughts or recommendations?

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  • FTP Server with advanced features

    - by Nikolas Sakic
    Hi, We supply zone-files to our customers. Some zone files are big about 300MB and some are quite small, maybe like 1MB. We had this issue that someone setup a script to continually download the file. Imagine downloading 300MB file a few hundred times a day. Since, we don't have packet-shaper to throttle the traffic, we need to upgrade ftp server and use add-on modules to limit the download somehow. We currently use proftpd server. Also note that there are different users for different domains - say, if you want to download zone file for .INFO domain, then you use a particular user. That user can't download any other zone's file. This is what we are looking for: Have maximum of 400MB download per user per day. Or even have different download limit for different users per day. Have one connection per user at any time. Max # of connection (non-simultaneous) per user per day is 5. Anyone trying to exceed that gets banned for 24 hours. Has anyone used FTP server with similar restrictions above? Does anyone have any ideas where I can start? Any help would be appreciated. Thanks. -N

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  • Running HTTP and HTTPS connections for a single domain (say, www.example.com) through a Cisco ACE SS

    - by Paddu
    My web application config has a Cisco ACE load balancing across a server farm and I want to use the ACE as an SSL endpoint as well. To make this work, the network architect has come up with a design where all secure pages have to be served from secure.my-domain.com, while non-secure pages are served up from www.my-domain.com. The reason for this is apparently that the configuring the Cisco ACE to accept HTTPS requests on port 443 for a particular public IP prevents the simultaneous acceptance of HTTP requests on port 80 for the same IP. While I'm not a networking (or Cisco) expert, this seems to be intuitively wrong, as it would prevent any website using the Cisco ACE to serve pages on http://www.my-domain.com and https://www.my-domain.com simultaneously. In this situation, my questions are: Is this truly a limitation of the Cisco ACE when used as an SSL endpoint? If not, then can I assume that we can set up the ACE to accept connections for a particular IP on ports 80 and 443, and function as an SSL endpoint for the incoming requests on 443? Links to appropriate documentation most welcome here. Assuming the setup in the previous question, can I then redirect both sets of requests to the same server farm on the same port?

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  • Software/hardware to build video streaming server?

    - by Sasha Yanovets
    I am looking for a video streaming server solution, something like online TV server, with ability to make live broadcasts in the internet. What software could you recommend for that? What kind of hardware it should run on, should be there anything special? I am looking for a solution that could be scaled up to at least 1000 simultaneous users online with good resolution of video. I think it is good to have general answer on what direction to choose. But here more details on my specific case: I just looking for a solution almost from scratch. We have some video content that we've produced, but it is not delivered over internet yet. We do not tied to any particular vendor for now. We want to make 24 hours of steaming three 8 hour blocks with change of content every day. We want the ability to make regular live broadcasts. I guess we will need to have several options of streaming quality (low ~56 kb/s mid ~273 kb/s). Some terms just foreign to me (like play-truncation rate), if you could point out what parameters we should avare of, it would be great. Uplink to the internet is to be determined. We plan to start from something and scale up on the way. If you are already have some kind of media streaming server, just describe its configuration here (hardware, OS, software), peak number of concurrent users it serves. I think it could help people approaching this task.

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  • Device CAL, User Cal or Processor license needed for SQL 2008 (architecture explained inside)?

    - by nycgags
    So we have a number of servers in the Amazon cloud running SQL Server Standard edition to aggregate data. For that purpose we are fine, the licensing is handled by our contract with Amazon, no problem there. For the beefier work, we want to install Enterprise Edition (EE) on our servers processing raw data so that we can take advantage of table partitioning. We currently have 3 servers aggregating data from about 40 node servers, all 43 of these servers are running standard edition which is fine. We also have 4 servers running standard processing the raw data, but I think we can get away with 2 (for redundancy) running Enterprise Edition. We have 2-3 dba's that access these DW servers for maintenance (using the same windows login via remote desktop). So visually: 40 -- 3 -- [2] -- 2 -- 1 nodes -- aggregators -- raw (which we want to run EE) -- calculators -- datawarehouse Nodes PUSH to aggregators, Raws PULL from aggregators, Calculators PULL from Raw, Calculators PUSH to datwarehouse I am specifying the push vs. pull in case that changes how the # of licenses is calculated. Q1) how many device (or user) CAL's do we need? Q2) do I need to speak with someone from MSFT to find out if it is ok to install in the Amazon Cloud (Amazon said we need to verify it is ok in our license terms)? Q3) what happens if another device tries to access a server with the limited number of device CAL's? Q4) Are the device CAL's simultaneous number of devices or total? Q5) Do Device and User CAL's cost the same or is there a difference? Q6) Would we need to buy a processor license (we are hoping not to)?

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  • Choosing gateway router/firewall for small datacenter network [closed]

    - by rvs
    I'm choosing a gateway router/firewall for small internal network for medium-sized web service. Currently there are 5 servers in internal network, up to 50 http(s) requests/second, up to 1000 simultaneous connections, uplink is 100 Mbit. So, network is relatively small and not very busy and we don't like to buy some pricey monster like cisco or jupiper for this site. Instead we'd like to buy two affordable devices (one for spare), which can handle our workload now and some time in future (it might be up to 2x more in 1 year). I had some experience with Sonicwall NSA, but it seems to be too complex for this site (we don't need most of its features) and even too pricey when buying two of them. So, after some research I've come up with following options: Netgear Prosecure UTM Series (probably UTM25) Zyxel ZyWall Series (USG100 or USG200) Sonicwall TZ 210 Is this a good idea? All of the above seems to be more office products, not datacenter ones. Or we should stick with Sonicwall NSA? Does anyone have any hands-on experience with this models? Maybe some other advices? Thanks.

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  • Software/hardware to build video streaming server?

    - by Sasha Yanovets
    I am looking for a video streaming server solution, something like online TV server, with ability to make live broadcasts in the internet. What software could you recommend for that? What kind of hardware it should run on, should be there anything special? I am looking for a solution that could be scaled up to at least 1000 simultaneous users online with good resolution of video. I think it is good to have general answer on what direction to choose. But here more details on my specific case: I just looking for a solution almost from scratch. We have some video content that we've produced, but it is not delivered over internet yet. We do not tied to any particular vendor for now. We want to make 24 hours of steaming three 8 hour blocks with change of content every day. We want the ability to make regular live broadcasts. I guess we will need to have several options of streaming quality (low ~56 kb/s mid ~273 kb/s). Some terms just foreign to me (like play-truncation rate), if you could point out what parameters we should avare of, it would be great. Uplink to the internet is to be determined. We plan to start from something and scale up on the way. If you are already have some kind of media streaming server, just describe its configuration here (hardware, OS, software), peak number of concurrent users it serves. I think it could help people approaching this task.

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  • Limited connections to Ubuntu 12.04 server

    - by Luis M. Valenzuela
    I'm having a weird problem with my server. The server is inside my network, connected to a 3com switch which is connected to the router that handles the internet connection. The main purpose of the server is to host a php application. What's happening is that user 1 to 15 in the private network have no problems connecting to the server, when user 16 tries to connect a time out comes out and is unable to connect to the server. It's not just to the php application, but to any service from the server. When the 15 users are using the application, the server doesn't even answer to ping. I haven't set any special limit in Apache's ini file or MySql and the firewall is being turned off because the server is only to give service to the internal network. Is there a parameter in any of the network's card conf. files that might me causing this ? Or should I suspect from the router's or switches configuration ? UPDATE. Tomorrow, I'm gonna do some test on the server modifying two kernel params in : /etc/sysctl.conf The settings are: net.core.somaxconn which has the limit on simultaneous network connections to the server and kernel.shmmax which controls the amount of memory the system can use for managing connections.

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  • User receives group membership error to terminal server even though has rights

    - by BlueToast
    http://www.hlrse.net/Qwerty/TSLoginMembership.png To log on to this remote computer, you must be granted the Allow log on through Terminal Services right. By default, members of the Remote Desktop Users group have this right. If you are not a member of the Remote Desktop Users group or another group that has this right, or if the Remote Desktop User group does not have this right, you must be granted this right manually. Only as of today a particular user began receiving this message for a second terminal server they use; otherwise, they have never had any problems authenticating into this server. We have no restrictions on simultaneous and multiple logins. On each terminal server, we have a group and security group like "_Users" locally in the Builtin\Remote Desktop Users group. For this particular user, on this particular terminal server we have locally given him Administrator, Remote Desktop Users, and Users membership; in AD we have given him DOMAIN\Administrator, Builtin\Remote Desktop Users, DOMAIN\_Users. It still gives us that error message. We gave him membership to another terminal server (random) by simply making him member of another DOMAIN\_Users group -- successfully able to login to that random terminal server. So, from scratch we created an AD account 'dummy' (username) with only Domain Users membership. Tried to login to this particular server, no success. So I added 'dummy' to DOMAIN\_Users group, and then was successfully able to login. Other users from this user's department are able to login to this particular server just fine as well. We checked the Security logs on this particular server, and while it is logging everything, the only thing it appears to not log are these failed login attempts from this particular user who receives this error message. We have tried rebooting the server, and the user is still receiving that error message.

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  • Concurrent users with Quickbooks?

    - by airietis
    I work in a company with 3 people who regularly use the same Quickbooks file. However, they work remotely on different networks. I need to implement a solution that allows all three of us to access Quickbooks at the same time remotely (and each make changes at the same time). We have a spare desktop PC that can be utilized as a server. So, my question is: what is the cheapest and most hassle-free solution to solving this problem? I've considered using application cloud hosting, however, it is very expensive ($40 per user a month) and we are on a tight budget. Is it possible to install Quickbooks on my own server, and have them connect to it remotely? If so, what is the best way to accomplish this? Remote desktop protocol? Or is there a built in feature for this with Quickbooks Premier 2013? EDIT: As MDMarra mentioned, I am looking for a solution that offers true simultaneous access. Will using a dedicated server and having users connect to a VPN be a viable solution?

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  • vmware server 64 bit on ubuntu 9.10 64 bit with P2V windows 2003 SBS poor network speed

    - by RobertHC
    configuration is ubuntu 2.6.31-21 64 bit vmware 2.0.2 64 bit last release hardware is core 2 quad with 8GB ram guest is win 2003 server SBS 32 bit Dear friends, we have a converted physical to virtual windows sbs 2003, converted with last converter available nowadays http://www.vmware.com/products/converter/ vCenter converter. Running the P2V 2K3 SBS on vmware server, it does boot fine, but we do note an abnormal CPU activity and a poor lan speed. As attempts we did what follow. We removed all unneeded peripherals, we removed one NIC (phisycal server was 2 nics), we changed the vmx to ged the nic recognized as intel instead than amd, we removed 1 cpu (physical was 2 cpu), we removed anything was reported as failed driver from system events monitor. Nothing to do, no way and funny results. Let's read some tests results. All are made with the same file copied in different source folders. Copying from client side (both directions copy, to/from server) results are i.e. 10 seconds, copying the same files from server side (again from and to server) results are different... from client to server, speed is round about (bit more) 10 seconds, but from server to client direction is slower: double the time. Beeing very fast and launching a simultaneous copy "from server to client"+"from client to server", this made from the server side, results in a stuck traffic... 45 seconds to do the copy. vmware tools are installed and e1000 driver has been updated. With one processor CPU activity is still going up and down but much less than with two. Because of test, we installed win 2k8 STD 64 bit. We repeated all the above tests with exactly the same file result is just one: always 5 seconds (this matches the lan speed) Any idea about this issue is welcome and thank you if any. Kind regards R.

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  • Getting input from keyboard

    - by SAMIR BHOGAYTA
    When you type on the keyboard the keystrokes go to a particular application, the active application. The active application receives the input from the keyboard. This means the application has input focus. There are two events for a key on a keyboard, when the key is pressed and when it is released. No it's not a single event as you might expect if you have no prior programming experience, in shooter games for example when you keep the forward key pressed (KeyDown) the player goes forward, and when it isn't pressed (KeyUp) the player stays put. The event that occurs when the key is pressed is called KeyPress. It occurs between KeyDown and KeyUp, and therefore acts similar to KeyDown. Similar to the way we handle OnPaint and other events we also handle the OnKeyDown event (because we want the event to occur when the key is pressed and not when it is released) by overriding it. Try the code below and test it. You will understand the role of each property. protected override void OnKeyDown(KeyEventArgs keyEvent) { // Gets the key code lblKeyCode.Text = "KeyCode: " + keyEvent.KeyCode.ToString(); // Gets the key data; recognizes combination of keys lblKeyData.Text = "KeyData: " + keyEvent.KeyData.ToString(); // Integer representation of KeyData lblKeyValue.Text = "KeyValue: " + keyEvent.KeyValue.ToString(); // Returns true if Alt is pressed lblAlt.Text = "Alt: " + keyEvent.Alt.ToString(); // Returns true if Ctrl is pressed lblCtrl.Text = "Ctrl: " + keyEvent.Control.ToString(); // Returns true if Shift is pressed lblShift.Text = "Shift: " + keyEvent.Shift.ToString(); } How do I find out when the user presses a specific key? As you probably imagine, this will be easily accomplished using 'if'. if (keyEvent.KeyCode == Keys.A) { MessageBox.Show("'A' was pressed."); } Probably most beginners would be tempted to do this: if (keyEvent.KeyCode == "A") .... which is definitely incorrect because we can't compare System.Windows.Forms.Keys to a string. Also note that in the example we are using 'keyEvent.KeyCode', that means that even if we have other shift keys pressed (Alt, Ctrl, Shift, Windows...) simultaneous with A, the if condition returns true because it doesn't recognize key combinations. If we want to ignore key combinations (Alt+A, Ctrl+Shift+A), etc. we need to use 'keyEvent.KeyData' of course: if (keyEvent.KeyData == Keys.A) { MessageBox.Show("'A', and only A, was pressed."); } When you right click on a file in Windows Explorer and you have the Shift key pressed you get the additional 'Open with...' item in the menu. This and many others are cases when you need to use the mouse button together with the keyboard. The following code will change the background color of the form only if the form is clicked while the Ctrl key on the keyboard is pressed. If the Ctrl key is unpressed and the form is clicked nothing happens. private void Form1_Click(object sender, System.EventArgs e) { Keys modKey = Control.ModifierKeys; if(modKey == Keys.Control) { this.BackColor = Color.Yellow; } } If you have further questions feel free to ask them and also check the following pages at MSDN: KeyUp Event KeyPress Event KeyDown Event

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  • Sweet and Sour Source Control

    - by Tony Davis
    Most database developers don't use Source Control. A recent anonymous poll on SQL Server Central asked its readers "Which Version Control system do you currently use to store you database scripts?" The winner, with almost 30% of the vote was...none: "We don't use source control for database scripts". In second place with almost 28% of the vote was Microsoft's VSS. VSS? Given its reputation for being buggy, unstable and lacking most of the basic features required of a proper source control system, answering VSS is really just another way of saying "I don't use Source Control". At first glance, it's a surprising thought. You wonder how database developers can work in a team and find out what changed, when the system worked before but is now broken; to work out what happened to their changes that now seem to have vanished; to roll-back a mistake quickly so that the rest of the team have a functioning build; to find instantly whether a suspect change has been deployed to production. Unfortunately, the survey didn't ask about the scale of the database development, and correlate the two questions. If there is only one database developer within a schema, who has an automated approach to regular generation of build scripts, then the need for a formal source control system is questionable. After all, a database stores far more about its metadata than a traditional compiled application. However, what is meat for a small development is poison for a team-based development. Here, we need a form of Source Control that can reconcile simultaneous changes, store the history of changes, derive versions and builds and that can cope with forks and merges. The problem comes when one borrows a solution that was designed for conventional programming. A database is not thought of as a "file", but a vast, interdependent and intricate matrix of tables, indexes, constraints, triggers, enumerations, static data and so on, all subtly interconnected. It is an awkward fit. Subversion with its support for merges and forks, and the tolerance of different work practices, can be made to work well, if used carefully. It has a standards-based architecture that allows it to be used on all platforms such as Windows Mac, and Linux. In the words of Erland Sommerskog, developers should "just do it". What's in a database is akin to a "binary file", and the developer must work only from the file. You check out the file, edit it, and save it to disk to compile it. Dependencies are validated at this point and if you've broken anything (e.g. you renamed a column and broke all the objects that reference the column), you'll find out about it right away, and you'll be forced to fix it. Nevertheless, for many this is an alien way of working with SQL Server. Subversion is the powerhouse, not the GUI. It doesn't work seamlessly with your existing IDE, and that usually means SSMS. So the question then becomes more subtle. Would developers be less reluctant to use a fully-featured source (revision) control system for a team database development if they had a turn-key, reliable system that fitted in with their existing work-practices? I'd love to hear what you think. Cheers, Tony.

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  • I need help with 2D collision response (of stacking rotating polygons, with friction and gravity, for a game)

    - by Register Sole
    Hi I am looking for suggestions on how to write a collision response for game programming purpose (so not a scientific simulation). I am dealing with 2D polygons that are rotating, and I want them to be able to stack. I also want friction and gravity. I have a detection mechanism that returns the separating axis, how long the polygons are overlapping, and up to 2 points of contact. For the response, I am currently using an impulse-based response, which main idea is: find the separating axis, length of overlap, and the point of contact (if there are two, pick a random point between to simulate averaged force. i believe there are better ways than this) separate the object (modifying their positions, taking into account of their masses. i do not separate them completely though, to keep track that they are colliding to reduce jitter) calculate normal force based on the coefficient of restitution as if there is no friction. calculate friction, as if there is no normal force. I also assume that the direction of the friction is the same throughout the collision. apply the two forces (which result in a rather inaccurate result, since each force is calculated as if the other is not present. for non-rotating bodies though, this method is exact) I am aware that this method requires the coefficient of friction to be sufficiently small due to the assumption that the direction of friction stays the same in a collision. Also, the result is visually satisfying if gravity is not present. However, when there is gravity, objects on ground jitter and drift (even with zero coefficient of restitution)! It also happens for stacking objects. Larger coefficient of restitution and gravity increase the jittering. I hope you can help me with this. Some things i would like to know more about is how to handle collision with two point of contacts (how to end up having an object sitting still on the ground?), how to reduce, and prevent if possible, jitter and drift (do people use the most accurate method possible, or is there a trick to overcome this?), and how to handle multiple objects collision (for example, in the case of stacking objects, how do I check collisions between all of them and keep them all stable at every frame so they don't jitter?). A total reformulation of my algorithm is also welcomed, as long as it works. Another thing to note is that I am not making a Physics game, so I only need a visually satisfying response (though a realistic response is preferable, if it is not performance-heavy). But surely jittering and drifting objects on flat ground are not at all acceptable. In addition, I am a Physics student, so feel free to talk about impulse and whatever needed. Finally, I'm sorry for the long post. I tried to be as concise as I can. Thank you for reading it! EDIT It seems what I didn't manage to come up all this time is to separate resting contact as a class of its own and how to solve them. Currently reading the paper suggested by Jedediah. More suggestions on the topic are welcome :) CASE CLOSED After reading various papers referenced in the paper, successfully implemented simultaneous impulse method (referring to the original paper by Erin Catto, [Catt05]). Thanks maaaan!! The paper is wonderful. The current system is visibly much better than the previous. Still haven't separated resting contact as a class of its own though, which brings me to my next question. Love you all! Haha (sorry, I'm just so happy thanks to you).

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  • What's slowing for loops/assignment vs. C?

    - by Lee
    I have a collection of PHP scripts that are extremely CPU intensive, juggling millions of calculations across hundreds of simultaneous users. I'm trying to find a way to speed up the internals of PHP variable assignment, and looping sequences vs C. Although PHP is obviously loosely typed, is there any way/extension to specifically assign type (assign, not cast, which seems even more expensive) in a C-style fashion? Here's what I mean. This is some dummy code in C: #include <stdio.h> int main() { unsigned long add=0; for(unsigned long x=0;x<100000000;x++) { add = x*59328409238; } printf("x is %ld\n",add); } Pretty self-explanatory -- it loops 100 million times, multiples each iteration by an arbitrary number of some 59 billion, assigns it to a variable and prints it out. On my Macbook, compiling it and running it produced: lees-macbook-pro:Desktop lee$ time ./test2 x is 5932840864471590762 real 0m0.266s user 0m0.253s sys 0m0.002s Pretty darn fast! A similar script in PHP 5.3 CLI... <?php for($i=0;$i<100000000;$i++){ $a=$i*59328409238; } echo $a."\n"; ?> ... produced: lees-macbook-pro:Desktop lee$ time /Applications/XAMPP/xamppfiles/bin/php test3.php 5.93284086447E+18 real 0m22.837s user 0m22.110s sys 0m0.078s Over 22 seconds vs 0.2! I realize PHP is doing a heck of a lot more behind the scenes than this simple C program - but is there any way to make the PHP internals to behave more 'natively' on primitive types and loops?

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  • Efficient Multiple Linear Regression in C# / .Net

    - by mrnye
    Does anyone know of an efficient way to do multiple linear regression in C#, where the number of simultaneous equations may be in the 1000's (with 3 or 4 different inputs). After reading this article on multiple linear regression I tried implementing it with a matrix equation: Matrix y = new Matrix( new double[,]{{745}, {895}, {442}, {440}, {1598}}); Matrix x = new Matrix( new double[,]{{1, 36, 66}, {1, 37, 68}, {1, 47, 64}, {1, 32, 53}, {1, 1, 101}}); Matrix b = (x.Transpose() * x).Inverse() * x.Transpose() * y; for (int i = 0; i < b.Rows; i++) { Trace.WriteLine("INFO: " + b[i, 0].ToDouble()); } However it does not scale well to the scale of 1000's of equations due to the matrix inversion operation. I can call the R language and use that, however I was hoping there would be a pure .Net solution which will scale to these large sets. Any suggestions? EDIT #1: I have settled using R for the time being. By using statconn (downloaded here) I have found it to be both fast & relatively easy to use this method. I.e. here is a small code snippet, it really isn't much code at all to use the R statconn library (note: this is not all the code!). _StatConn.EvaluateNoReturn(string.Format("output <- lm({0})", equation)); object intercept = _StatConn.Evaluate("coefficients(output)['(Intercept)']"); parameters[0] = (double)intercept; for (int i = 0; i < xColCount; i++) { object parameter = _StatConn.Evaluate(string.Format("coefficients(output)['x{0}']", i)); parameters[i + 1] = (double)parameter; }

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  • SQL Exception: "Impersonate Session Security Context" cannot be called in this batch because a simul

    - by kasey
    When opening a connection to SQL Server 2005 from our web app, we occasionally see this error: "Impersonate Session Security Context" cannot be called in this batch because a simultaneous batch has called it. We use MARS and connection pooling. The exception originates from the following piece of code: protected SqlConnection Open() { SqlConnection connection = new SqlConnection(); connection.ConnectionString = m_ConnectionString; if (connection != null) { try { connection.Open(); if (m_ExecuteAsUserName != null) { string sql = Format("EXECUTE AS LOGIN = {0};", m_ExecuteAsUserName); ExecuteCommand(connection, sql); } } catch (Exception exception) { connection.Close(); connection = null; } } return connection; } I found an MS Connect article which suggests that the error is caused when a previous command has not yet terminated before the EXECUTE AS LOGIN command is sent. Yet how can this be if the connection has only just been opened? Could this be something to do with connection pooling interacting strangely with MARS? UPDATE: For the short-term we have implemented a workaround by clearing out the connection pool whenever this happens, to get rid of the bad connection, as it otherwise keeps getting handed back to various users. (Not too bad as this only happens a couple of times a day.) But if anyone has any further ideas, we are still looking out for a real solution...

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  • ServerIdentity memory leak with IHttpAsyncHandler

    - by Anton
    I have a .NET web application that consists of a single HTTP handler class that implements IHttpAsyncHandler. All requests to this handler are handled asynchronously, though some requests are short-lived and some are long-lived (nothing over a few seconds). The problem is that memory consumption grows over time as requests are handled. All profiling results point to an unbounded growth of String objects held by instances of System.Runtime.Remoting.ServerIdentity. Every String value is different, but they all look similar to: /dd41c00e_1566_4702_b660_c81cdea18a43/vigefresi5pfv8n0ekddg57z_1154.rem There is nothing in my application that uses ServerIdentity directly, and unless I am mistaken, the ServerIdentity instances are proportional to the number of incoming requests. If this is an internal .NET structure, it looks like the CLR is not cleaning up after itself. What could be causing the leak? UPDATE A little less than half of the String objects are being held by System.Runtime.Remoting. The remaining String objects are being held by System.Runtime.Serialization and look similar to: +1sgess5rjcrgbmp3kqr6bmv_3474.rem Also, the problem only seems to occur when lots of simultaneous HTTP web requests arrive.

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  • XMLHttpRequest leak in javascript. please help.

    - by Raja
    Hi everyone, Below is my javascript code snippet. Its not running as expected, please help me with this. <script type="text/javascript"> function getCurrentLocation() { console.log("inside location"); navigator.geolocation.getCurrentPosition(function(position) { insert_coord(new google.maps.LatLng(position.coords.latitude,position.coords.longitude)); }); } function insert_coord(loc) { var request = new XMLHttpRequest(); request.open("POST","start.php",true); request.onreadystatechange = function() { callback(request); }; request.setRequestHeader("Content-Type","application/x-www-form-urlencoded"); request.send("lat=" + encodeURIComponent(loc.lat()) + "&lng=" + encodeURIComponent(loc.lng())); return request; } function callback(req) { console.log("inside callback"); if(req.readyState == 4) if(req.status == 200) { document.getElementById("scratch").innerHTML = "callback success"; window.setTimeout("getCurrentLocation()",5000); } } getCurrentLocation(); //called on body load </script> What i'm trying to achieve is to send my current location to the php page every 5 seconds or so. i can see few of the coordinates in my database but after sometime it gets weird. Firebug show very weird logs like simultaneous POST's at irregular intervals. Here's the firebug screenshot: IS there a leak in the program. please help.

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  • Using Java Executor on AppEngine causes AccessControlException

    - by Drew
    How do you get java.util.concurrent.Executor or CompletionService to work on Google AppEngine? The classes are all officially white-listed, but I get a runtime security error when trying to submit asynchronous tasks. Code: // uses the async API but this factory makes it so that tasks really // happen sequentially Executor executor = java.util.concurrent.Executors.newSingleThreadExecutor(); // wrap Executor in CompletionService CompletionService<String> completionService = new ExecutorCompletionService<String>(executor); final SomeTask someTask = new SomeTask(); // this line throws exception completionService.submit(new Callable<String>(){ public String call() { return someTask.doNothing("blah"); } }); // alternately, send Runnable task directly to Executor, // which also throws an exception executor.execute(new Runnable(){ public void run() { someTask.doNothing("blah"); } }); } private class SomeTask{ public String doNothing(String message){ return message; } } Exception: java.security.AccessControlException: access denied (java.lang.RuntimePermission modifyThreadGroup) at java.security.AccessControlContext.checkPermission(AccessControlContext.java:323) at java.security.AccessController.checkPermission(AccessController.java:546) at java.lang.SecurityManager.checkPermission(SecurityManager.java:532) at com.google.appengine.tools.development.DevAppServerFactory$CustomSecurityManager.checkPermission(DevAppServerFactory.java:166) at com.google.appengine.tools.development.DevAppServerFactory$CustomSecurityManager.checkAccess(DevAppServerFactory.java:191) at java.lang.ThreadGroup.checkAccess(ThreadGroup.java:288) at java.lang.Thread.init(Thread.java:332) at java.lang.Thread.(Thread.java:565) at java.util.concurrent.Executors$DefaultThreadFactory.newThread(Executors.java:542) at java.util.concurrent.ThreadPoolExecutor.addThread(ThreadPoolExecutor.java:672) at java.util.concurrent.ThreadPoolExecutor.addIfUnderCorePoolSize(ThreadPoolExecutor.java:697) at java.util.concurrent.ThreadPoolExecutor.execute(ThreadPoolExecutor.java:652) at java.util.concurrent.Executors$DelegatedExecutorService.execute(Executors.java:590) at java.util.concurrent.ExecutorCompletionService.submit(ExecutorCompletionService.java:152) This code works fine when run on Tomcat or via command-line JVM. However, it chokes in the AppEngine SDK Jetty container (tried with Eclipse plugin and the maven-gae-plugin). AppEngine is likely designed to not allow potentially dangerous programs to run, so I could see them completely disabling thread creation. However, why would Google allow you to create a class, but not allow you to call methods on it? White-listing java.util.concurrent is misleading. Is there some other way to do parallel/simultaneous/concurrent tasks on GAE?

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  • Looking for a lock-free RT-safe single-reader single-writer structure

    - by moala
    Hi, I'm looking for a lock-free design conforming to these requisites: a single writer writes into a structure and a single reader reads from this structure (this structure exists already and is safe for simultaneous read/write) but at some time, the structure needs to be changed by the writer, which then initialises, switches and writes into a new structure (of the same type but with new content) and at the next time the reader reads, it switches to this new structure (if the writer multiply switches to a new lock-free structure, the reader discards these structures, ignoring their data). The structures must be reused, i.e. no heap memory allocation/free is allowed during write/read/switch operation, for RT purposes. I have currently implemented a ringbuffer containing multiple instances of these structures; but this implementation suffers from the fact that when the writer has used all the structures present in the ringbuffer, there is no more place to change from structure... But the rest of the ringbuffer contains some data which don't have to be read by the reader but can't be re-used by the writer. As a consequence, the ringbuffer does not fit this purpose. Any idea (name or pseudo-implementation) of a lock-free design? Thanks for having considered this problem.

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  • multithreading in c#

    - by Lalit Dhake
    Hi, I have console application. In that i have some process that fetch the data from database through different layers ( business and Data access). stores the fetched data in respective objects. Like if data is fetched for student then this data will store (assigned ) to Student object. same for school. and them a delegate call the certain method that generates outputs as per requirement. This process will execute many times say 10 times. Ok? I want to run simultaneously this process. not one will start, it will finish and then second will start. I want after starting 1'st process, just 2'nd , 3rd....10'th must be start. Means it should be multithreading. how can i achieve this ? is that will give me error while connection with data base open and close ? I have tried this concept . but when thread 1'st is starting then data will fetched for thread 1 will stored in its respective (student , school) objects. ok? when simultaneous 2'nd thread starts , but the data is changing of 1'st object ,while control flowing in program. What have to do?

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  • STLport crash (race condition, Darwin only?)

    - by Jonas Byström
    When I run STLport on Darwin I get a strange crash. (Haven't seen it anywhere else than on Mac, but exactly same thing crash on both i686 and PowerPC.) This is what it looks like in gdb: Program received signal EXC_BAD_ACCESS, Could not access memory. Reason: 13 at address: 0x0000000000000000 [Switching to process 21097] 0x000000010120f47c in stlp_std::__node_alloc_impl::_M_allocate () It may be some setting in STLport, I noticed that Mac.h and MacOSX.h seemed far behind on features. I also know that it it must be some type of race condition, since it doesn't occur just by calling this method (implicity called). The crash happens mainly when I push the system, running 10 simultaneous threads that do a lot of string handling. Other theories I come up with have to do with compiler flags (configure script) and g++ 4.2 bugs (seems like 4.4.3 isn't on Mac yet with Objective-C support, which I need to link with). HELP!!! :) Edit: I run unit tests, which do all sorts of things. This problem arise when I start 10 threads that push the system; and it always comes down to std::string::append which eventually boils down to _M_allocate. Since I can't even get a descent dump of the code that's causing the problem, I figure I'm doing something bad. Could it be so since it's trying to execute at instruction pointer 0x000...000? Are dynlibs built as DLLs in Windows with a jump table? Could it perhaps be that such a jump table has been overwritten for some reason? That would probably explain this behavior. (The code is huge, if I run out of other ideas, I'll post a minimum crashing sample here.)

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